This invention is related in general to processing of digital information and more specifically to a system for rights management of digital media including limiting the number of copies that can be made from a digital medium.
The digital format has quickly become the format of choice for many types of information including audio, video, computer data, etc. For example, today's Compact Disk-Read-Only Memory (CDROM) media are used to store audio files such as songs, narration, etc., onto a small disc that can be played back with a CDROM drive. The CDROM can also be used to write and read video content and data files. Another popular media format is the Digital Versatile Disk (DVD) that is similar in basic approach to the CDROM in that it is a disc-shaped optical media that is read with a drive mechanism using a laser. The DVD format is becoming popular to deliver high-quality audio and video (e.g., full-length movies) content.
Other physical media formats exist such as a “memory stick” that uses flash-memory or another form of persistent solid-state random access memory (RAM). A mini-disc format uses magnetic media, as do the current form of “micro” hard disk drives. Other media formats exist such as magnetic, optical, solid state, etc.
Although digital media is a low-cost way to provide high-quality content to end users, such as listeners, viewers, or computer users, one problem with using digital media distribution is that the media can be easily copied. Typically the copying occurs without any additional compensation to the content owner, distributor or other controlling authority.
Some approaches are being considered to try to prevent unwanted copying. For example, a digital watermark approach puts identifying information in association with a physical medium, such as a CDROM, or can embed the identifying information in a portion (or throughout) the digital information on the medium. For example, bits can be used throughout a song to identify the owner of the content and to indicate any use restrictions. One problem with this approach is that the amount of bits for watermarking can take away from the capacity of the medium to store the intended content. Also, the watermarking can degrade the quality of the content.
Another approach is to use a separate, discrete portion of the medium to store copy control, or rights management information. The copy control information can be read and/or written by the drive mechanism (i.e., playback device), by a copying system such as a computer, or by other devices that may be used to write or read information on the medium. For example, a DVD can be provided with a “generation” count. That is a user can purchase an original DVD with a generation count of 3. When a first generation copy of the original DVD is made then the generation count on the first generation copy is set to 2. When a second generation copy is made the second generation copy has a count that is set to 1. When a third generation copy is made then the generation count is set to 0 and no further copies will be allowed.
While the generation count approach can have some success at preventing massive, exponentially growing numbers of copies from propagating, there can still be a very large number of copies spawned from the original DVD. For example, a purchase of the original DVD might make any number of first generation copies (e.g., one million or more) that will each have a generation count set to 2. With this approach it is not possible to limit the total number of copies deriving from any given one of the original or subsequent first or second generation copies.